Dusts are small solid particles, created by the breakage of larger particles that are usually the product of an industrial activity such as grinding, polishing, drilling, baulking, etc. Also, in addition to dusts there are fumes, mists and vapors, which are also part of industrial activities.
Dust collectors are devices that extract air with particles of dust or various materials of a process, directing the flow of extracted air to a tiller device, which separates dust or particles of materials from the airstream that is sent then into the atmosphere through discharges of clean air. These devices are used to, either, collect valuable material in a process, wherein said material is in the form of solid particles or dusts, or to remove polluting or unwanted material, likewise, wherein said material is in the form of solid particles or dusts.
Dust collectors are used to collect dust generated in different processes in the industry, they are used to recover the product and send it back to the process or to control areas with rising dust where health, hygiene, cleaning and the environment can be affected. In both cases, the correct selection of the dust collector represents energy and resource savings, as well as the option to recover the collected dust, for possible reuse.
In the art, a dust collector is defined by a device which sucks, using an airstream normally generated by a centrifugal fan, solid particles which are transported in ducts and introduced into said collector first in a dirty air chamber which is also called “dirty chamber”. This air then passes through a medium, filter, or also called filter fabric, to a second inner chamber of the collector called clean air chamber or also called “dirty chamber”, with the solid particles remaining on the outside of the filter. The clean chamber and the dirty chamber are separated from each other by a plate or “mirror” with holes where the filters are placed, of so that there is only communication between the two chambers through said filters or filter medium. The subject matter of said filter medium varies according to the application, environment and size of the dust to be collected.
Dust collectors, typically use one of two types of filter means such as textile technology and paper or cellulose technology called bag filters and cartridge filters. Both may now include synthetic fibers or polymers in addition to surface finishes and treatments in an attempt to cover the range of pollutants and mixtures of pollutants generated in the industrial processes.
Thus, in a constant use, the filters tend to become saturated, since the dusts are adhered in said filters causing a reduction in the flow in the side of the clean chamber, therefore, it is necessary to clean the filters of the excess of dusts during the same use while maintaining said dust collector. Nowadays, the most used means of cleaning the filters is the so-called PulseJEt which consists of pulses of compressed air coming from at least one jet pipe or flute pointing at the filter from the clean chamber periodically cleaning it. This compressed air pulse is applied in direction opposite to the general flow and passes into of each filter through a venturi which creates a secondary air of several times its volume, this effect causes the dust adhered in the surface layer of the filter to be removed to fall into a hopper by gravity and it is subsequently accumulated in a storage bin.
The jet pipe has a compressed air tank, this pipe is attached and closed at one end and opened on the opposite side, leaving the pipe on the outside of the clean air chamber, to connect to a diaphragm valve having an electrically operated valve coupled and these in turn are connected to the timer, which regulates the interval between the compressed air blasts and the duration thereof, which in turn is controlled by a central unit, that is, the collector is operated automatically at predefined time intervals.
The product removed from the filters is collected in the hopper, wherein said product can be exhausted through a rotary valve, helical conveyer, etc.
Also, it is common in the art to add an optionally electronic differential manometer, which indicates the pressure difference between the two chambers resulting from the saturation of the filter with the pollutant by circulating a flow rate through the filter medium, automatically starting the self-cleaning system defined by the compressed air blasts in accordance with said pressure difference detected.
In order to implement a dust collector system, all factors already known in the art, such as location, number of extraction points to machines or workstations and their corresponding configuration, characteristics of the type or types of pollutant, toxicity, level of explosiveness, size, density and shape of the pollutant particle, standards and regulations, energy or power required for capture-transport-filtration, safety elements, temperature, etc. must be considered.
In this respect, it is important that the filters operate with the flow rate designated during the design stage of the system, wherein there is a corresponding air-fabric ratio considering the varying saturation of the filters.
Additionally, in the art it has been identified that the fan power is dimensioned considering that the filters are saturated, that is, a saturation power or also called full power.
Also, it has been identified that at full fan power and using new filters, the filters' service-life is reduced compared to non-new filters, since said full power with new filters is reflected in a higher flow rate, therefore, the air-fabric ratio is forced, that is, the pollutant particles reach said new filters with at a relatively high speed whereby they are deeply embedded in the fibers of the filter making it more difficult to detach them. In certain cases, said particles may penetrate or break said filter.
Likewise, in the art, the way in which a saturation in the dust collector filters is identified through a comparison between a pressure measurement in the dirty chamber and the environment pressure assuming that any change in the pressures means a saturation or non-saturation of said filters, so that before this condition the flow rate is adjusted. That is, based on the differences of static pressure measurements between the environment and the dirty chamber, the power of the collector is adjusted to reach to the value corresponding to the design flow rate, or initial operating parameters.
However it has been identified that this art presents several imprecisions, since the pressure difference can be originated by factors external to said saturation or non-saturation of a filter, since the ductwork of the dust collector is likely to present accumulations which saturate said ductwork, since it is common for pollutants other than the expected dusts to be absorbed at the workstations usually due to some human error such as fabrics, bottles, paper, waddings, among other work elements whereby a system considering these factors is desirable. This is common in dust collector systems wherein there is a plurality of workstations with complex non-linear duct systems.
In this respect, it has also been identified that once the dust has been collected in a bin or container, the speed at which said bin is saturated varies depending on the dust collected, the workstations, etc., wherein once the bin is saturated, the collector operates imprecisely, since the saturation of the bin causes the dusts not to be ejected, which also causes the filters to saturate. In this respect, techniques have been developed to monitor the saturation of the bin, however, these techniques are not sufficiently precise with respect to providing continuous measurements, which is desirable to identify when it is necessary to empty said bin.
Thus, it is desirable to develop a dust collector control system which prevents the reduction of the new filters' service-life through actual-time adjustments. Additionally, it is desirable to develop a dust collector control system that allows monitoring and control of the variables involved in the collection process, so that the corresponding adjustment is allowed in real time and in advance. Likewise, it is desirable for the system to include continuous and actual-time monitoring of the saturation level of the bin. Likewise, based on the data, measurements and calculations, it is possible to evaluate algorithms to make predictions about system components' faults or service-life.